JCOG 2019;29(3):88-93 88 ndometriosis, which is poorly understood in a pathophysiological sense, is a hormone-dependent inflammatory chronic gynecological disease. It is described as the presence of ectopic endometrial glands and stroma outside the uterine cavity and is associated with pelvic pain, dys- menorrhea, and infertility. 1 Retrograde menstruation, menstrual tissue im- plantation, and impaired immune response are the most commonly observed conditions. Endometriosis is a fairly common condition, prevalent in ~10% of the women of reproductive age. An estimated 176 million women are affected by this disease worldwide. 2 An increase in the overall cancer incidence in patients with endometriosis has been reported by var- ious studies. However, little is known about the effect of endometriosis on cancer survival. 3 Most of the previous investigations on the impact of endometriosis on cancer had focused on its relation to ovarian cancer. Therefore, while the re- lationship between endometriosis and ovarian cancer is well known, its as- Does Endometriosis Impact the Prognosis of Endometrial Cancer? ABSTRACT Objective: Despite the well-known relationship between endometriosis and the risk and prognosis of ovarian cancer, studies on the association the two are rare. Moreover, the impact of endometriosis on the prognosis of endometrial cancer has not been described in the literature. In this study, we attempted to investigate whether endometriosis had an effect on the prognosis of endometrial cancer. Material and Methods: This retrospective study was carried out on data from endometrial cancer patients between January 1996 and February 2016 at the Gynecological On- cology Department of Çukurova University Balcalı Hospital in Adana, Turkey. The pathological reports of 920 cases, operated after the diagnosis of endometrial cancer, were screened. Among these cases, 764 patients were found to be eligible for enrollment in this study. The patients were distributed into two groups based on the presence or absence of endometriosis in the pathological materials. The prognosis of the groups was compared using the Kaplan-Meier method. Results: The endometriosis group was associated with younger age, less parity, more infertility, and a higher risk of simultaneous ovarian cancer. There were non-significant differences between the groups re- garding pathological risk factors such as myometrial invasion, lymphovascular space involvement, lymph node positivity, and stage of progression. No recurrences or deaths were observed in the en- dometriosis group, although this observation was not statistically significant. Conclusion: It is sug- gested that endometriosis does not influence the prognosis of endometrial cancer. However, a conclusive assessment could not be made by this study alone and, therefore, further studies are needed and researchers are encouraged to focus more on this subject. Keywords: Endometrial cancer; endometriosis; endometriosis-associated cancers Ghanim KHATIB a , İsa TEMUR b , Ümran KÜÇÜKGÖZ GÜLEÇ a , Ahmet Barış GÜZEL a , Mete SUCU a , Emine BAĞIR c , Derya GÜMÜRDÜLÜ c , Mehmet Ali VARDAR a a Department of Obstetrics and Gynecology, Çukurova University Faculty of Medicine, Adana, TURKEY b Clinic of Obstetrics and Gynecology, Kahramanmaraş Necip Fazıl City Hospital, Kahramanmaraş, TURKEY c Department of Pathology, Division of Gynecologic Pathology, Çukurova University Faculty of Medicine, Adana, TURKEY Received: 12 Jun 2019 Received in revised form: 20 Jul 2019 Accepted: 22 Aug 2019 Available online: 22 Oct 2019 Correspondence: Ghanim KHATIB Çukurova University Faculty of Medicine, Department of Obstetrics and Gynecology, Adana, TURKEY ghanim.khatib@gmail.com Copyright © 2019 by Türkiye Klinikleri DOI: 10.5336/jcog.2019-70088 ORIGINAL RESEARCH